Mine roof bolt plate



1A. CURRY m 2,854,824

MINE 300 BOLT PLATE Filed-June 14, 1956 Oct. 7, 1958 EEEW W A INVE OR WILLIAM C.' MP BELL VIRGIL A CURRY MINE ROOF BOLT 'PLATE Virgil A. Curry, Dehue, W. Va., and William C. Campbell, Youngstown, Ohio Application June 14, 1956, SerialNo. 591,397 ,3 Claims. (Cl. 614 5) -In coal and other mining operations expansion bolts are frequentlyinserted in holes drilled in vthe roofs of the tunnels and set against a plate interposed between the head of each bolt and under face of the roof to afford support to the latter, and the present invention is directed generally to the improvement of such plates including their adaptation for reception of means forsupporting electrical cables, conduits, air pipes and the likeextended within the tunnel, the convenient, out-of-theway and safe disposition of which has been a rather difi'icult problem since some may be dangerous to contact and of course all must be so disposed they will not be injured by or interfere with normal mining operations, conditions impossible to fulfill when they are merely laid on the floor or strung along the side walls of the mine.

It is therefore a principal object of our invention to provide an improved roof strengthening and reinforcing plate which without impairment of its usefulness for this purpose is adapted for reception of means for supporting conduits for electrical, air or water services and the like.

Another object is to provide a roof retaining plate for subterranean spaces which may be easily and simply secured in place to become a more or less permanent fixture, and yet one adapted to receive as well as to release, either at installation or later, cable and hose supporting brackets which may be positioned to suit the needs of the immediate area in the vicinity of the plate as desired.

Other objects, purposes and advantages of the invention will hereafter more fully appear or be understood from the following description of a preferred embodiment of it with reference to the accompanying drawing, in which:

Fig. 1 is a bottom perspective view of the plate itself;

Fig. 2 is a top perspective view thereof; and

Fig. 3 is a vertical section showing the plate positioned in supporting relation to a mine roof with the aid of a toggle bolt which may be deemed typical of many specific components which may be used for this purpose, utility conduit brackets being also shown in association with the plate in this figure, the section of the plate corresponding to one taken on the line 33 in Fig. 2 and typical utility conduits supported in the brackets being indicated in broken lines.

Referring now more particularly to the drawing, and first especially to Figs. 1 and 2, it will be appreciated the plate generally designated 1 is approximately square and may be made of anysuitable sheet or plate material of adequate physical properties conveniently by cutting or stamping it from the flat stock and then forming it in a suitable press, soft steel plate of approximately thickness being preferred when the plate is roughly about 10" square in overall dimensions.

Centered at approximately the intersection of the plate diagonals is provided a bolt hole 2 about which there is a flat annular bearing surface 3 an inch or more in radial width surrounded in turn by a substantially semitates Patent '10 (Fig. 3) comprising straight shanks ed annular surface 6.

Outwardly of the dished area 4 and ring surface '6 the plate is for the most ,partflat in the planeof bearing surface 3 and retainer area SZbutinwardlyfrom each of its corners along its diagonals'there is provided a groove 7 of generally semi-circular'cross section produced by suitably deforming the plate in the same direction as in the dished area 4, these grooves'providing with "a' mineroof or the like .whenthe plate is inpositionithereagainst, sockets 8 for reception of. hook-shaped brackets '10 adapted to seat in but not fully ,fill the grooves.

When the;plates are to beinstalled in a mine, for example .at spaced intervals. along the .ceiling or roof R of a passageway therein, aplurality of suitably spaced vertical holes H are drilled upwardly from the ceiling surface preferably for -a depth sufiicienrto penetrate a fairly dense and stable overlying structure such as a rock stratum or the like, and a toggle or expansion bolt B to which a washer W is applied is then passed through hole 2 in the plate and entered into hole *H in the roof. By setting up the bolt B through application of a wrench to its head the plate may be drawn toward the roof and prior to its snug engagement therewith the shanks or one or more of brackets 10 may he slipped respectively into sockets 8 so that after the plate by further tightening of the bolt is firmly clamped against the mine ceiling the bracket shanks are likewise clamped between the latter and the walls of the respective grooves 7, thus positioning the brackets to receive and support service conductors such as conduits C, C.

While this method of operatively assembling the brackets with the plates will usually be preferred, under some circumstances a like end result can be obtained by driving each bracket shank into its groove just before or sometimes even after the plate is in final position; to facilitate this the free ends of the shanks may be tapered or pointed.

As the eflect of each plate in holding the roof in position, supported as it were through the bolt from a superjacent relatively stable earth structure, extends not only vertically upward above the plate itself but also outwardly beyond its edges for a distance depending on the cohesiveness of the formation of the roof, it is usually not essential the plates be closely spaced to afford adequate roof support and the distances between adjacent plates is therefore to be governed by local conditions.

Moreover in instances in which their relatively close spacing is indicated by such conditions it may not be essential that every plate be equipped with brackets 10 as the service lines to be supported by the latter may only require support at more widely spaced intervals in which case, for example, the brackets may be omitted from alternate plates, or used only with every third, fourth or even larger number of plates.

The invention thus constitutes a distinct improvement in the art in that, among other things, it provides a plate which may be readily produced at low cost and due to its peculiar formation is more resistant to deformation under vertical stress imposed on it when clamped against the mine roof than a flat plate of equal thickness and area, yet which moreover may be utilized to effectively, securely and removably support up to four brackets for carrying conduits, wires or the like adjacent the mine ceiling.

While we have herein described one embodiment of the invention with considerable particularity and have referred to some of its uses under conditions which are subject to variation in different localities or even in.

parting from the spirit and scope of the invention as hereinafter claimed. 7

Having thus described our invention, we claim and desire to protect by Letters Patent of the United States:

1. A mine roof bolt plate having a central substantially flat annular bearing surface adapted to engage the mine roof, a generally toroidal portion ofiset from the plane of and surrounding said bearing surface and a substantially square peripheral edge portion extending approximately in the plane of said surface and having grooves offset from said plane in the same direction as said toroidal portion extending respectively diagonally inward from the several intersections of adjacent sides of the edge portion.

2. Means for supporting a mine ceiling or the like comprising a bolt extending upwardly through the ceiling into the mine roof and a bolt plate secured thereby in contact with the ceiling, said plate having a substantially square peripheral edge portion, grooves offset from the plane of said portion extending diagonally inward respectively from the intersections of adjacent sides thereof and forming with the ceiling substantially semi-cylindrical sockets, a substantially toroidal portion inwardly of said edge portion extending convexly downward away from the ceiling and a central substantially annular bearing portion having a surface engaging the ceiling and an opposite surface cooperative with the bolt head for holding the plate against the ceiling with the bolt shank extending through the plate substantially axially of said bearing portion.

3. In combination with the supporting means defined in claim 2, a bracket having a rectilinear shank extending into one of said sockets and frictionally retained therein by engagement with the superjacent portion of the ceiling, and an integral depending hook portion outwardly of the plate adapted for reception of a conduit or the like.

References Cited in the file of this patent UNITED STATES PATENTS 678,155 Bailey July 9, 1901 815,813 Graham Mar. 20, 1906 2,748,594 Edwards June 5, 1956 

